<!DOCTYPE html>
<html lang="en">

<head>
  <meta charset="UTF-8">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>Document</title>
  <style>
    .box {
      width: 200px;
      height: 200px;
      background-color: skyblue;
      /* background-color: orangered; */
      transition: all 2s linear 500ms;
      /* 过渡属性  持续时间  过渡类型  延迟时间 */

    }

    .box:hover {
      background-color: orangered;
      width: 600px;
      height: 500px;
      opacity: 0.1;
    }
  </style>
</head>

<body>

  <div class="box">

  </div>
</body>

</html>